package com.dz.lm.common.utils.security;

import java.io.UnsupportedEncodingException;

/**
 * ?* @author TaoWuHua
 * ?* @description:?
 * ?* @date :2019/6/10 12:00
 * ?
 */
public class Base64Utils {
        private static char[] base64EncodeChars = new char[]
                { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
                        'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
                        'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
                        '6', '7', '8', '9', '+', '/' };
        private static byte[] base64DecodeChars = new byte[]
                { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,
                        54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
                        12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
                        30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
                        -1, -1, -1 };

        /**
         * 加密
         *
         * @param data
         * @return
         */
        public static String encode(byte[] data)
        {
            StringBuffer sb = new StringBuffer();
            int len = data.length;
            int i = 0;
            int b1, b2, b3;
            while (i < len)
            {
                b1 = data[i++] & 0xff;
                if (i == len)
                {
                    sb.append(base64EncodeChars[b1 >>> 2]);
                    sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
                    sb.append("==");
                    break;
                }
                b2 = data[i++] & 0xff;
                if (i == len)
                {
                    sb.append(base64EncodeChars[b1 >>> 2]);
                    sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
                    sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
                    sb.append("=");
                    break;
                }
                b3 = data[i++] & 0xff;
                sb.append(base64EncodeChars[b1 >>> 2]);
                sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
                sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
                sb.append(base64EncodeChars[b3 & 0x3f]);
            }
            return sb.toString();
        }

        /**
         * 解密
         *
         * @param str
         * @return
         */
        public static byte[] decode(String str)
        {
            try
            {
                return decodePrivate(str);
            } catch (UnsupportedEncodingException e)
            {
                e.printStackTrace();
            }
            return new byte[]
                    {};
        }

        private static byte[] decodePrivate(String str) throws UnsupportedEncodingException
        {
            StringBuffer sb = new StringBuffer();
            byte[] data = null;
            data = str.getBytes("US-ASCII");
            int len = data.length;
            int i = 0;
            int b1, b2, b3, b4;
            while (i < len)
            {

                do
                {
                    b1 = base64DecodeChars[data[i++]];
                } while (i < len && b1 == -1);
                if (b1 == -1)
                    break;

                do
                {
                    b2 = base64DecodeChars[data[i++]];
                } while (i < len && b2 == -1);
                if (b2 == -1)
                    break;
                sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));

                do
                {
                    b3 = data[i++];
                    if (b3 == 61)
                        return sb.toString().getBytes("iso8859-1");
                    b3 = base64DecodeChars[b3];
                } while (i < len && b3 == -1);
                if (b3 == -1)
                    break;
                sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));

                do
                {
                    b4 = data[i++];
                    if (b4 == 61)
                        return sb.toString().getBytes("iso8859-1");
                    b4 = base64DecodeChars[b4];
                } while (i < len && b4 == -1);
                if (b4 == -1)
                    break;
                sb.append((char) (((b3 & 0x03) << 6) | b4));
            }
            return sb.toString().getBytes("iso8859-1");
        }
}
